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Updated: Jul 17, 2026

The Immediate Partial Removal of Cumulus-Oocyte Complexes: A Refined Approach for Rapid Observation of In Vitro Fertilization
Published on: October 18, 2024
Prospective evaluation of the optimal time for selecting a single embryo for transfer: day 3 versus day 5
Nicolas H Zech1, Bernard Lejeune, Francoise Puissant
1Institute for Reproductive Medicine and Endocrinology, Bregenz, Austria. zech@ivf.at
Abstract:
To determine the best day for the selection and transfer of a single embryo, a prospective, randomized study was undertaken that compared the ongoing pregnancy rate (PR) after single embryo transfer (SET) on day 3 with that after single blastocyst transfer (SBT) on day 5. Our results show an overall significantly higher PR after SBT (32.8%) compared with SET (23.2%), and a PR of 40.8% after SBT versus 25.6% after excellent-quality embryos became available.

